Going Viral

The Line Islands Collection

By Andreas Haas

In the run-up to an upcoming expedition to the Southern Line Islands in fall of 2013, a collection of related articles has been launched in the open access journal PeerJ. Two of the manuscripts presented in this paper collection show the use oxygen optodes to visualize micro-scale oxygen gradients at coral-algal interfaces and for biological oxygen demand.

Another study investigates how different functional groups of benthic primary producers, like corals, calcifying-, macro- and turf- algae "culture" up different microbes and thereby alter the microbial community metabolism.

This series of studies was driven by the demand to better understand the mechanisms underlying the alterations in coral reef community compositions as a result of human disturbance. The focus hereby lies on interaction processes between the microbial community and macro-organisms, like fish, coral, or algae, and on the reciprocal effects of both micro- and macro- organisms on key water parameters like oxygen, carbon, or nutrient concentrations.

The joint efforts of different laboratories specialized in multiple scientific disciplines allow for a more facetted view on the task of detecting overarching mechanisms which shape the structure of these different communities. Thanks to the opportunity provided by the newly established open-access online journal PeerJ, we can present these studies together in one confluent paper collection (https://peerj.com/collections/1-line-islands/) and will add further studies to the Collection arising from our continuing efforts. This new concept will enable other researchers to better conceptualize these and future findings in their broader context.

Bacteriophage adhering to mucus provide a non-host-derived immunity

The protective layer of mucus on the body's surface serves both as an entry point for pathogens and a home for large populations of beneficial microbes. This mucus layer harbors a large diversity of both bacteria and phage. We show elevated concentrations of phage on all mucosal surfaces sampled, ranging from cnidarians to humans, compared to the surrounding environment.

Using bacteriophage T4 and various in vitro tissue culture cells as a model system, Jeremy J. Barr et. al. demonstrate that this increase in phage abundance is mucus-dependent. This phage-mucus association reduces bacterial attachment and colonization of the mucus, which subsequently protects the underlying epithelium from bacterial infection. Enrichment of phage in mucus occurs via binding interactions between variable glycan residues displayed in mucus and immunoglobulin-like protein domains exposed on phage capsids.

Based on these observations we propose the Bacteriophage Adherence to Mucus (BAM) model that provides a ubiquitous, but non-host-derived, immunity applicable to mucosal surfaces. This benefits the metazoan host by limiting mucosal bacteria, and benefits the phage through more frequent interactions with bacterial hosts. BAM suggests the first demonstration of a symbiotic interaction between phage and metazoan hosts that provides a previously unrecognized immunity that actively protects mucosal surfaces.